USB Power versus External 7-12VDC

Using Arduino Project Guidance
1

Hello,

I am working on a project that utilizes your Arduino UNO board with an Arduino Ethernet shield.
Below are links discussing the powering of the Arduino UNO board. Since the Ethernet shield is powered from the 5V output of the Arduino UNO board, do you recommend an external source of 7-12V be utilized instead of 5V from a USB?

Thanks

2

ptavernelli:
do you recommend an external source of 7-12V be utilized instead of 5V from a USB?

Yes - for one simple reason. If you use a wall wart, you have a pretty good idea of the power available. It is written on the wall wart and is likely to be more than you need. If you use a USB cable, the power available is less obvious and, since the Ethernet shield is not famous for its low power requirement, may be less than you need.

A few years ago I had Arduino gear running fine on USB, and then I installed a new motherboard in the PC. In that instance, the backlight in the LCD was the straw that broke the camel's back.